Influenza infection rate has increased, but epidemiological activity is on a downward trend

The incidence of influenza syndrome in Portugal rose to 8.8 per 100,000 inhabitants, compared to 5.2 last week.

The epidemiological activity of influenza is trending downward in Portugal, according to the National Institute of Dutor Ricardo Jorge (INSA), but nevertheless, the incidence of influenza syndrome has risen to 8.8 per 100,000 inhabitants.

According to the Influenza Epidemiological Surveillance Bulletin for the period between 18 and 24 April (week 16), the incidence of acute respiratory infection (ARI) followed a rise and also rose to 8.8 per 100,000 population (5.2 in the previous week).

According to INSA, three cases of influenza were reported this week by 17 intensive care units (ICUs) that sent information (all due to influenza A). Two of the patients had a chronic illness and had not been vaccinated against seasonal influenza.

Since the beginning of the season, 25 cases of influenza have been reported by the intensive care units cooperating in surveillance, all due to influenza A virus.

The two wings that sent the information reported one case of influenza (influenza A virus). Since the beginning of the season, 19 influenza cases have been reported by the monitoring collaborating wards and influenza A virus has been identified in each of them.

In the 2021/2022 season, the laboratories of the Portuguese Network of Laboratories for Influenza Diagnostics (hospitals) recorded 97,163 cases of respiratory infection and 5,763 cases of influenza were identified.

In week 16 (April 18 to 24), 446 positive cases of influenza virus were identified, all of them type A.

To date, 119 cases of influenza virus and SARS-CoV-2 have been detected.

In the bulletin, INSA also says that since the start of the 2021/22 season, other respiratory factors have been identified in 4,965 cases. In the week that the bulletin indicates, there were 74 cases.

Altogether, up to Week 16 (18 to 24 April), 204 influenza viruses with antigenic properties different from the virus contained in the 2021/2022 influenza vaccine had been characterized.

Influenza vaccination began in Portugal at the end of September, earlier than usual due to the Covid-19 pandemic, and more than 2.5 million people have been vaccinated.

The INSA bulletin also states that deaths from all causes are “within expectations for this time of year.”

Regarding the European situation, she reports that in week 15 (11-17 April), several countries in the central and western part of the European region had a laboratory detection rate of influenza virus above 30%: the Netherlands (74%), France (55% ), Luxembourg (53%), Poland (47%), Norway (42%), Estonia (37%), Switzerland (36%), Italy (32%), Serbia (31%) and Spain (30%).